Use of Ethephon as a Plant Growth Regulator in Corn Production

Ethephon (2-chlorethylphosphonic acid), a plant growth regulator used widely on horticultural and agronomic crops, may reduce lodging and enhance yield in field corn (Zea mays L.). Field research was conducted in 1985 near Evansville, WI on a Seweba silt loam (fine loamy over sandy or sandy-skeletal, mixed, mesic Typic Argiaquoll) and in 1986 at the Arlington Research Station near Arlington, WI on a Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll) to determine ethephon application parameters influencing corn yield, kernel breakage, plant and ear height, lodging, and harvesting time. Four rates (0, 140, 280, and 560 g ha⁻¹) of ethephon were applied at three application times [tassel elongation (TE), TE + 7 d, and ear elongation (EE)] to four corn hybrids each year. Pioneer Brand hybrid 3377 showed increased yields with increasing ethephon rates up to 280 g ha⁻¹ while all others (Pioneer hybrids 3737,3732,3475, and two single crosses LH74 ✕ LH51 and LH145 ✕ LH182) showed decreased yields. A 0.77 Mg ha⁻¹ (7.6%) yield increase using 280 g ha⁻¹ occurred with Pioneer Brand hybrid 3377 in 1985. Early application showed less yield decrease than later timings. Grain yield per ear was increased 3% on hybrid 3377 and decreased 12% on hybrid 3737 by the high rate of ethephon. Plant and ear height were decreased up to 20% both years with the high rate of ethephon. In 1986, high rates of ethephon decreased lodging 63% and harvesting time 20% on corn harvested late in the season. Under conditions conducive to lodging, ethephon used at the high rate and early application time may preserve yields and allow for easier harvesting. If lodging is not a problem, ethephon applied to certain hybrids at high rates and late application times may reduce yields. Contribution from the the Dep. of Agronomy, Univ. of Wisconsin-Madison.